After a start to the season which we might euphemistically describe as ‘sub-optimal’, Arsenal have at least received some good news this week ahead of their high-pressure game against West Ham. Laurent Koscielny, by far the best central defender at the club, is back in training after tearing his Achilles last season in the second leg of Arsenal’s Europa League semi-final against Atletico Madrid.

While Koscielny is far from infallible as a defender – occasionally skittish as he is under pressure and ever eager to tackle off his feet – his absence has been felt keenly this season. As will have been evident to anyone who watched Arsenal’s opening defeats to Manchester City and Chelsea, in terms of agility, reliability and reading of the game there is nobody else in the Arsenal back four who currently comes close.

Asked in his press conference on Thursday when Koscielny would be available for selection, Unai Emery said: “It’s difficult to know. You look at this morning, he’s running, he’s working on the pitch. The progress is very good progress.” Arsenal’s new manager will have to hope that Koscielny continues his recovery ahead of schedule. His return is a central piece of the defensive jigsaw for the Gunners, though unfortunately many of the pieces that Emery has to work with have been bent out of shape, chewed at the edges and in some cases jumbled up in the wrong box completely.

Shambolic defence

Shkodran Mustafi is left on his backside by Alvaro Morata (Getty Images)

Arsenal’s defensive problems go back way before Emery’s arrival. Having finally hit upon a decent centre-back pairing in the 2012/13 season by combining Koscielny and Per Mertesacker – this after a series of farcical experiments featuring Mikael Silvestre, William Gallas, Philippe Senderos, Johan Djourou, Sebastien Squillaci and to a lesser extent Thomas Vermaelen – Arsene Wenger’s subsequent attempts at defensive recruitment were muddled at best.

With Wenger seemingly unwilling to spend large amounts of money on a premium central defender to replace the ageing Mertesacker, Gabriel Paulista was the first mid-range option to be brought into the club in 2015. When he proved to be a walking positional disasterclass with a disciplinary record to rival Charles Bronson, Shkodran Mustafi was acquired in a mirror-image deal the following year. Mustafi, too, arrived from La Liga with a reputation as a mercurial but promising defender, but he too has proved to be desperately inadequate for Arsenal’s needs. Meanwhile, the collection of young, English defenders acquired under Wenger have failed to make much of an impact at the club, with Calum Chambers now on loan at Fulham, Rob Holding not quite fully trusted and Cohen Bramall seemingly nowhere near the first team.

All of that leaves Emery with a massively tangled mess to sort out in the coming months. Though there were signs in their defeat to Chelsea last weekend that Arsenal’s attack can excel this season, the back four look as inept as they did in the bleakest periods of the late Wenger era. Mustafi, in particular, is a weak link, not helped by what looks like a collapse in confidence. He was turned inside out by Alvaro Morata for Chelsea’s second goal at Stamford Bridge, a moment which encapsulated the back-foot defending for which he has so often been criticised.

Add to that Hector Bellerin’s slump in form and the waning powers of Petr Cech, and the entire back five appears to be in disarray with the possible exception of Nacho Monreal at left-back. While Monreal is a reliable defender relative to some of his teammates, Emery will have to hope he remains injury-free given that Sead Kolasinac and Ainsley Maitland-Niles are both out of action for around eight weeks. That is another reminder of how pressing Arsenal’s problems across the back line have become. For Emery, this is where the real work as a coach and a strategist has to begin.

Liverpool’s example

Though Arsenal fans might instinctively prickle at comparisons to Liverpool – not so long ago a source of comfort to them as a once-great club fallen even further out of Premier League contention, but now in the midst of a renaissance under Jurgen Klopp which can only be a source of sea-green envy – their rivals have shown the way when it comes to defensive recruitment over the last season. Rather than baulk at the newly inflated prices being slapped on defenders and goalkeepers, Liverpool have accepted that new economic reality and decisively recruited from the best players available in their major problem positions.

Virgil van Dijk is living proof of how drastically a single signing in defence can alter a team’s fortunes, with Liverpool transformed from inconsistent also-rans to Champions League finalists after his arrival last January. While Alisson Becker has only made two competitive appearances since signing in the summer, he is already showing signs he could hugely improve Liverpool’s back five this season. The pair were brought in for a combined £142m, a sum which is admittedly monstrous. Ethical concerns aside, the hard truth is that restructuring a faulty defence is neither cheap nor easy in the modern era.

By contrast, Arsenal’s strategy of overhauling their defence via mid-level signings and inexperienced youngsters has been painfully ineffective. Gabriel, Mustafi, Holding and Chambers were signed for somewhere around £64m altogether, a far smaller sum than Liverpool have spent but with far less value for money in return. Arsenal would surely have been better off spending that sum on one excellent defensive acquisition, as opposed to a series of gambles, maybe men and ‘ones for the future’. They have been left with a defence which is somehow both understocked and overstaffed: a back five like a failing high-street retailer.

While Unai Emery does not have the all-encompassing influence of Arsene Wenger – chief scout Sven Mislintat now has a major role to play in the squad restructuring process – he must nonetheless make sure that defensive remodelling is made a priority at the club. The signing of Stephan Lichtsteiner and Sokratis in the summer suggests that both Emery and Mislintat know this. At just under £18m and with some limitations to his game already apparent, however, Sokratis will have to prove he is not another skimped and insufficient fix, while signing the 34-year-old Lichtsteiner on a free transfer seemed more like canny opportunism than long-term problem solving.

Given that Emery seems set on a high defensive line and a progressive passing game which starts at the back, he needs personnel capable of executing his tactical vision. Arsenal can have a renaissance of their own in the next few seasons under Emery, but not if they continue with such inadequate options – and so flawed a recruitment strategy – in such an important area of the pitch.

We know that sometimes it’s easier for us to come to you with the news. That's why our new email newsletter will deliver a mobile-friendly snapshot of inews.co.uk to your inbox every morning, from Monday to Saturday.

This will feature the stories you need to know, as well as a curated selection of the best reads from across the site. Of course, you can easily opt out at any time, but we're confident that you won't.

Oliver Duff, Editor

By entering your email address and clicking on the sign up button below, you are agreeing to receive the latest daily news, news features and service updates from the i via email. You can unsubscribe at any time and we will not pass on your information.